MXPA99001356A - Fusion of reacti metal materials - Google Patents

Abstract

Method and apparatus for melting reactive metallic materials, such as for example titanium-based alloys, other reactive alloys, by selective induction heating and sequences of a plurality of solid alloy filler components segregated in a refractory casting vessel in a manner to effect fast melting from top to bottom avoiding the damaging reaction of melting with refractory casting vessel material and fusion contamination

Description

FUSION OF REAGENT METALLIC MATERIALS The present invention relates to a method and apparatus for melting reactive alloys in high volumes at a reduced cost if there is no harmful contamination resulting from the reactions between the reactive melt and the containment materials of the present invention. fusion BACKGROUND OF THE INVENTION Many alloys with high percentages by weight of a reactive metal, such as titanium, react with air and most of the most common crucible refractories to the extent that the alloy is contaminated to an unacceptable limit. As a result, it is common to cast such alloys in metal crucibles (eg co) cooled with water using electric arc or induction to generate heat in the cast alloy charge. U.S. Patents 4 738 713 and 5 033 948 are representative of said casting techniques. Titanium and aluminum alloys that form intermetallic compounds, such as TiAl, have received considerable attention in recent years for use in the aerospace and automotive industries in service applications where their high resistance to high temperature and relatively light weight are highly desirable However, the intermetallic alloys contain a large part of titanium (for example the so-called TiAl range includes 66% by weight of Ti with the remainder being essentially Al) which make melting and casting without difficulty of contamination and high cost. US Pat. No. 5,299,619 to Chandley and Flemings discloses a casting and casting technique for reactive metals and alloys, including those that form intermetallic compounds, wherein the heating and melting of a solid titanium filler in a crucible The ceramic is accelerated by a strong exothermic reaction with a molten aluminum filler component that is melted separately and then introduced into the crucible for contact with the titanium filler component. The reduced residence time of the molten filler components reduces the potential contamination of the melt by reaction with the solids materials. Unfortunately titanium-based alloys, such as Ti-6AI-4V, have insufficient aluminum present in the alloy composition to effect the strong exothermic reaction with titanium in the melting vessel to practice rapid melting, the reduced contamination technique of U.S. Patent 5 299 619. Since such titanium-based alloys with "little aluminum" are in widespread use, there is a need for a melting method that can provide rapid, low-cost fusion of such alloys Reactive "scarce aluminum" with reduced contamination of the melt. It is an object of the present invention to provide the method and apparatus that satisfy the aforementioned need for a melting method and apparatus that can provide fast, low cost and reduced contamination fusion of "scanty aluminum" titanium-based alloys. as well as other reactive alloys having compositions incapable of a strong exothermic reaction in a melting vessel. In another object of the present invention to provide a method and apparatus for melting reactive metal materials in a refractory melting vessel using selective and sequential induction heating of various components of solid metal fillers segregated in a refractory crucible in a manner to effect the Top-down fusion of components that prevents harmful contamination from melting. It is another object of the present invention to provide the method and apparatus useful for melting reactive metal materials in a refractory melting vessel in a top-down manner that eliminates the need for a separate melting stage of a filler component which has hitherto been has melted first and then added to the container.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides the method and apparatus useful for the melting of reactive metal materials by selective and sequential induction heating of a plurality of solid alloy filler components segregated in a refractory melting vessel in a manner to effect rapid melting of top down which avoids the damaging reaction of the melt with the material of the refractory melting vessel and the contamination of the melt. The present invention can be practiced to melt reactive metallic materials such as titanium-based alloys with "scarce aluminum" as well as other reactive alloys, such as zirconium-based and iron-based alloys, which have compositions incapable of Strong exothermic reaction in a fusion vessel. In addition, the present invention can be practiced for melting reactive metallic materials, such as TiAl and other alloying alloys of intermetallic compound, having compositions capable of strong exothermic reaction without the need for a separate melting step of a component. of cargo. In an illustrative embodiment of the present invention, alloying elements of higher melting point of a reactive alloy are placed as solid charge components in an underlying position, such as in a lower region, of a refractory melting vessel and the elements The low melting point alloy is placed as solid charge components in an overlying position such as above the highest melting point load components in the vessel. For example, only to form a TÍ-6AI-4V reactive melt, high-melting solid titanium and vanadium filler components are dispersed near the bottom of the melting vessel under a solid charge component of high melting point. lower melt comprising at least partially aluminum jute with optional lower and / or higher melting point metals. Then, the upper portion of the charge is selectively heated by induction in the melting vessel to increase its temperature over that of the lower portion of the charge. Subsequently, both the upper and lower portions are heated by induction at the higher energy input to quickly melt the upper portion of the charge followed by the melting of the charge from the lower portion to form a molten alloy in a very long melting time. short, such as for example only 1 to 3 minutes, to reduce the residence time of the melt in the refractory melting vessel. In particular, the upper portion of the load exhibits a higher resistivity as a result of being preheated at a higher temperature and therefore generates more heat by induction heating at the higher energy input. The lower melting point component melts first, the alloys with the upper portion of the charge, and flows to the bottom of the melting vessel as a result. As the top-to-bottom melting of the charging components occurs, the molten alloy is kept substantially away from the side walls of the melting vessel by the input of the high-inductance coil to reduce the adverse reaction between the alloy melted and the refractory material of the container. In addition, the lower center of the higher melting charge component is the last region of the melting charge and reduces the adverse reaction of the molten alloy with the refractory material at the bottom of the melting vessel. The melting alloy can be cast from the melting vessel using conventional gravity or gravity casting techniques as soon as the melt is at an appropriate casting temperature to also reduce residence time and melt contamination. The present invention is advantageous in that a wide variety of reactive alloys can be rapidly melted with reduced contamination including thousands of reactive alloys having compositions incapable of strong exothermic reaction in a melting vessel. further, there is no need for a separate melting stage to separately melt a filler component which is then to be added to the melting vessel, thereby simplifying and reducing the cost of melting and casting the reactive alloys. In addition, the use of selective and sequential induction heating of a plurality of solid alloy charge components segregated in a refractory melting vessel in a manner for effecting rapid top-down melting allows the use of conventional crucible refractory materials in the fusion of reactive alloys, while the harmful contamination of the reactive alloy melt is still reduced. These and other objects and advantages of the present invention will be better understood from the following detailed description of the invention taken with the following drawings.

DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional side view. Schematic of the apparatus according to an embodiment of the invention for melting and counter-gravity casting of a reactive alloy melt. Figure 2 is similar to Figure 1 with the fill pipe submerged in the reactive melt.

DESCRIPTION OF THE INVENTION The present invention provides the method and apparatus for quickly melting a wide variety of reactive metallic materials, such as for example titanium-based alloys only, zirconium-based alloys, and iron-based alloys, having unsuitable compositions for practicing rapid fusion, reduced contamination technique for U.S. Patent 5 299 619 as well as reactive alloys, such as TiAl and other intermetallic compound forming alloys, having suitable compositions for practicing the patented rapid fusion technique. Importantly, the last reactive alloys can be melted according to the present invention without the need for a separate melting step. Reactive binary, tertiary, quaternary and other alloys can be melted by the practice of the present invention. An illustrative binary alloy comprises an alloy of titanium and aluminum which includes 66% by weight of Ti and the remainder essentially Al and which predominately forms the well-known TiAl range intermetallic compound. This reactive alloy can be melted according to the invention without the need to separately melt the aluminum alloy component. An exemplary tertiary alloy may include an alloy of titanium, aluminum and other metal, such as the well known Ti-6AI-4V alloy where the numbers represent the percentages by weight of the alloying elements. The Ti-6AI-4V alloy has insufficient aluminum to effect the strong exothermic reaction with titanium as described in U.S. Patent 5 299 619. Representative reactive alloys that can be melted according to the present invention are described in the Examples set forth below for purposes of illustration only and not as a limitation. Referring to Figures 1-2, the apparatus for practicing one embodiment of the present invention is illustrated as including a mold section 10 and a melting section 12 with the mold section 10 positioned over the melting section. 12 for counter-flow casting of the reactive melt up into the mold section. A mold container 20 is movable relative to the fusion section 12 by a hydraulically operated arm (not shown) as illustrated in U.S. Patent 5 042 561, the teachings of which are incorporated herein by reference. For this end . The mold section 10 includes a steel container 20 having a central chamber 20a in which an inversion mold 22 having a plurality of mold cavities 24 is placed in a mass 26 of particles of low reactivity. The mold 22 rests on an elongate refractory filling pipe (eg carbon) 23 which hangs therefrom outwardly from the container 20. The filling pipe 23 is attached to the bottom of the mold 22 and extends in a sealed manner through the mold. a bottom opening in the container 20 as shown, for example, in U.S. Patent 5 042 561. A mold sprue 28 is communicated 28 is communicated to the filling pipe 23 and to the mold cavities 24 by means of inlets 31. The inversion mold 22 is formed by the well-known process described in U.S. Patent 5 299 619, the teachings of which are incorporated herein by reference. The mold container 20 includes an opening / closing lid 25 connected to the container by means of a hinge 25a. The cover has a rubber sheet j 29 communicated to the atmosphere through the ventilation opening 21. The mold is embedded in the selected particle mass 26 to exhibit low reactivity to the particular reactive alloy that is melted and cast into the mold 22 so that in the event of any melt spill from the mold 22, the melt will be confined in a manner without harmful reaction in the mass 26. The particles suitable for a representative TiAI melt comprise mulita grain or zirconia of mesh size from -20 to +50. The particles can be selected from other materials if desired depending on the reactive alloy to be cast. The rubber gasket 29 compacts the particle mass 26 around the mold 22 when a relative vacuum is removed in the container 20 so that the mold 22 is held externally during casting as it is filled with molten alloy. The mold container 20 includes a peripherally extending chamber 36 communicated by means of a conventional on / off valve 38 to a vacuum source 40, such as a vacuum pump. The chamber 36 is filtered by a perforated filter 41 selected to be impermeable to the dough particles 26 to confine them within the container 20. The mold container 20 also includes an inlet duct 37 for admitting argon or other inert gas from a duct of suitably sieved distribution 43 of the container from a suitable inert gas source 47. The mold section 10 can be of the type described and shown in detail in the aforementioned U.S. Patent 5 299 619. The casting section 12 includes a metal casting enclosure (e.g. steel) 50 which forms a chamber a casting chamber 52 around a refractory casting vessel or crucible 54. The casting enclosure 50 includes a side wall 56 and a portion thereof. removable top 58 sealed to the side wall by means of a hinged sel. A sliding cover 61 of the type set forth in U.S. Patent 5,042,561 is placed in a fixed cover 59 of the upper part 58 and is slidable to receive the filling pipe 23 for the purposes set forth in the patent. The fixed cover 59 includes an opening 59a for the mold filling pipe 23. The sliding cover 61 includes an opening 61a for receiving the filling pipe 23 when the openings 59a, 61a are aligned to counter-melt the fusion from the vessel 54 within the mold 22. According to one embodiment of the apparatus of the invention, a water-cooled induction coil 68 is provided around the melting vessel 54. The induction coil 68 includes a selectively energizable segment 68a encompassing the region above the melting vessel 54 and a lower segment 68b integral with the first upper segment 68a and encompassing a lower region of the melting vessel. Preferably, the segment 68a comprises about 1/3 of the melting vessel 54; that is, the upper 1/3 region of the melting vessel. Segment 68b covers much of the remaining 2/3 region of the melting vessel. Alternatively, the invention may be practiced using a separate upper induction coil corresponding to a hollow water cooled coil segment 68a and a separate water cooled induction coil corresponding to a lower coil segment 68b. Each of the upper coil and the separated lower coil would have two electrical conductors corresponding to the conductors L to the power source S so that the upper coil could be selectively fed by the preheating charge component C2 and the upper coils and lower could be fed to melt the charge components C 1, C 2 as described below. The side wall 56 includes a sealed inlet port 66 for the passage of the conductors of its electric power minister L which connect the couplings 69a, 69b, 69c to the electric power source S by means of the switch SW. The power source may comprise a conventional solid-state frequency converter, although the invention is not limited to any particular energy source. The electrical couplings 69a, 69b, 69c are connected to opposite ends of the upper coil segment 68a to provide means for electrically energizing the upper segment 68a, while the couplings 69a, 69b are connected to opposite ends of the upper and lower segments 68a , 68b to provide means for electrically energizing the complete coil 68; that is, both upper and lower segments 68a, 68b. A switch SW associated with the power source S is connected as shown in Figures 1 and 2 so that the electrical couplings 69a and 69c can be powered by the power source S to selectively energize the upper coil segment 68a and also so that the electrical couplings 69a and 69b can be powered by the power source S to feed the entire coil 68. The electrical coupling 69b is connected to the coil 68 on its rotatable lower part so that the turns of the lower part can provide structural support to the crucible and maintain the energy conductors from the metal support flanges 84, 84b. The side wall 56 also includes a port 70 communicated by means of a conduit 72 and a valve 74 to a source 76 of argon or other inert gas and, alternatively, to a vacuum source (for example the vacuum pump) 78. The side wall 56 further includes an annular shoulder or flange 84 on which multiple coil supports 86 are seated circumferentially and seated to support the induction coil 68. The flange includes an outer annular shoulder or flange 84a attached to an inner annular shoulder or flange 84b in which coil supports are placed to support the induction coil 68. A mass 1 19 of low reactivity particles, such as 100-mesh zirconia powder, extending upwardly between coil 68 and the container fusion 54 to confine any smelting that may be spilled or otherwise escaped from the vessel 54 within the low reactivity particles. The melting vessel or crucible 54 comprises an indian tubular ceramic shell 90 having a bottom 90a, which may be integral with the tubular crucible section or a separate component attached to the tubular crucible section. For casting titanium-based fusions, the crucible 54 comprises mulite-faced ceramic with zirconia 54. For casting titanium-based castings, the mold 22 comprises a zirconia or internal yttrium front coating or external aluminum backing layers that form the mold body (for example, see U.S. Patent 4,740,246). The total mold wall thickness can be from 0.25 to 0.176 cm. The internal front cladding is selected to display as much, only the minor reaction with the casting of the titanium-based casting therein to minimize contamination of the cast iron. A preferred mold front coating for casting titanium-based castings is applied to a transient mold pattern as a paste comprising zirconia and fluoro zirconia liquid, dry, and fused alumina coated (mesh size) 80). A front coating layer is typically applied. Preferably, the backing layers for use with this front coating are applied as a paste comprising ethyl silicate and tabular alumina liquid, dried, and coated with molten alumina (36 mesh size). The open upper end of the casting vessel 54 may be partially closed by a closing plate 100 made of fibrous alumina. The plate 100 includes the central opening 102 through which the filling pipe 23 can be extended as shown in Fig. 2. The lower closed end of the casting vessel 54 can include an outer shoulder or flange 10 which couples the In the same way, a similar shoulder or flange 120 is held, which holds the cover or closure of the access port 122. For the purposes of further using an embodiment of the method of the invention for melting a Ti-6AI-4FV alloy, a component of solid lower charge (underlying) C1 of the elementary titanium solid parts (shown as chips) and elemental solid vanadium parts (shown as solid black pieces) interspersed together are placed as the solid charge component (comprising approximately 2/3 of the height of the total charge in the casting vessel) in the lower region of the casting vessel 54 as illustrated, for example, in Figure 1. The lower load component C 1 may be laminated or placed in layers to include elementary titanium parts near the bottom of the casting vessel 54 to comprise approximately one half of the load component C 1 and a mixture of solid parts of elementary titanium and interleaved vanadium solid pieces placed to overcome the lower titanium parts to comprise the remaining half of the load component C 1. The titanium parts and the vanadium parts can be mixed before the introduction into the casting vessel 54 or can be mixed as or after they are introduced into the casting vessel. Alternatively, the titanium-vanadium alloy parts can be introduced at 2/3 of the casting vessel where the load C1 resides. The titanium and vanadium parts have respective melting points of 1669.66 ° C and 1900.4 ° C, thus constituting the higher melting point components of the total melt to be compared, for example, for the remaining aluminum loading component that has a melting point of 660.52 ° C. In addition to or instead of vanadium, the titanium parts can be interspersed with pieces of other metals such as molybdenum, chromium, niobium, silica and others, which are present in some titanium alloys. Niobium is typically present in the form of a major alloy of, for example, niobium and aluminum as a result of the difficulty in melting niobium due to its very high melting point. Those other metals (eg, molybdenum, chromium, niobium, silica and others) would typically be dispersed with titanium parts in a stratified charge component or in C1 layers where the elemental titanium parts are placed close to the bottom of the casting vessel to comprise about one half of the load component C 1 and a mixture of solid pieces of elementary titanium and pieces of other metals are placed on the lower titanium parts to comprise the remaining half of the load component C 1. Although a predominant amount of the other metal parts are dispersed with the titanium parts in the stratified charge component C 1 as described, some smaller amount of the other metal parts may be dispersed in the top loading component C2 as the casting vessel 54 is loaded. After the aforementioned lower solid charge component C 1 comprising titanium interlaced with some vanadium or Other metals as described above were introduced into the storage container, the lower melting point C2 load component comprising solid aluminum parts (shown as round shot or particles) and titanium parts were introduced into the interior. from the top 1/3 of the casting vessel 54 in the upper region of the casting vessel to overlap the solid charge component with the highest melting point C 1 (for example titanium and vanadium parts). The aluminum parts of the load component C2 can be loaded with titanium parts to disperse the aluminum parts for preheating and improve the reaction capacity of the molten alumina with the titanium parts present. The charge component C 1 may include aluminum interlaced with a metal of lower melting point (for example tin) used in some titanium alloys (for example Ti-5AI-2.5Sn alloy).

The solid titanium parts may comprise titanium trim sheet, briquettes, pieces or other shapes. The titanium trim sheets are typically 2.54 cm by 2.54 cm by 0. 158 cm in size and obtained from Chemalloy Co. The briquettes are made of titanium sponge up to dimensions of approximately 2.54 cm by 2.54 cm by 7.62 cm. The titanium filler component is added in an amount to provide the desired Ti% by weight in the metal melt. The vanadium source may comprise vanadium or alloy shot, trim sheet or other forms. For example, the vanadium-aluminum alloy is typically provided in the form of -8 to +50 mesh grains. The vanadium loading component is added in an amount to provide the desired wt% of V in the alloy foundry. The solid aluminum parts may comprise aluminum trimming sheet, shot or other shapes. For example, aluminum is typically provided in the 0.635 cm shot form. The aluminum filler component is added in an amount to provide the% by weight of that desired in the alloy foundry. For loading, the casting container 54 is assembled and held in the cover 122. The casting vessel 54 with the removed plate 102 is manually loaded with the solid charge components C 1, C 2 as described above. The loaded casting vessel 54 is placed inside the induction coil 68 as shown in Figure 2 with the cover or seal 122 sealed against the enclosure 50 and with the removable top 58 removed from the enclosure 50. The particles 1 19 (for example zirconia grain) are placed around the casting vessel 54 as shown in Figure 2 through the open enclosure 50. After the particles 1 19 have been added and the plate 102 is placed back into the casting vessel 54, the upper part 58 is sealed in the enclosure 50. At the beginning of the casting / casting cycle for the Ti-based casting, the casting chamber 52 is first evacuated to less than 0.2 torr (200 microns) and then it is re-argonized with argon to slightly above atmospheric pressure (controlled to a pressure of 1 torr) by means of port 70. After according to one embodiment of the invention, the coil segment 68aa (or the separate upper coil) is selectively fed by means of the electrical conductors L via coupling 69a, 69c and the energy source S to inductively and selectively preheat the top loading component C2 (for example, mainly the aluminum parts and titanium) in the casting vessel 54 to an increased temperature over the temperature of the first charging component C1. Typically, the top charge component C2 is preheated by selectively induction to an increased temperature determined by the alloy to be melted and cast. If multiple charge components are present in the upper melting charge component c2, all components are heated and melted according to their physical properties (e.g., melting points). The preheating by selective induction of the top load component C2 increases the temperature thereof and therefore increases the resistivity of the load component C2. The load component with the highest melting point C 1 in the lower region of the melting vessel 54 is heated only minimally by energizing the coil segment 68a so that its temperature remains close to the ambient temperature in the background of the casting vessel 54. For illustration purposes only, a C2 charging component comprises 0.77 kg of aluminum and 3.30 kg of titanium can be preheated by induction selectively at an energy level of 180 to 200 kilowatts by energizing the coil segment 68a for a time of 7 to 7.5 minutes. The temperature of the charging component C2 therefore rises to about 81.5 ° C to about 954.4 ° C., which is above the melting point of the alumina of 660 ° C and below the melting point of titanium of 1669.6 ° C. After heating by selective induction of the second charging component C2 the second preheated metal charging component C2 in the upper region of the casting vessel 54 and the first charging component C1 in the lower region of the casting vessel are heated by I nduction and fusing by energizing the entire induction coil 68 which includes the segments 68a, 68b (or separate upper / lower coils) by means of electrical conductors L via the couplings 69a, 69b at a much higher energy level . Since the upper load component C2 exhibits a higher resistivity as a result of being preheated by induction selectively up to the increased temperature (superambiente) and therefore generates more heat by induction heating at the higher energy input, the component load C2 (which includes mostly aluminum and titanium parts) is first melted thereby and flows to the bottom of the casting vessel 54. As the top-to-bottom casting of the charging components C2, C1 occurs, the molten alloy formed in this manner is held substantially away from the side walls of the vessel 54 by the high level of induction energy to reduce the adverse reaction between the molten alloy and the refractory material of the vessel. In addition, the bottom center of the higher melting point load component C 1 is the last region of the melt charge and reduces the adverse reaction of the molten alloy with the refractory material at the bottom of the vessel 54. For purposes of illustration only, a lower loading component C 1 comprising 8.01 kg of titanium and 0.77 kg of vanadium and the top loading component C2 comprising 0.77 kg of aluminum and 3.30 kg of titanium can be heated by induction and melted at a level of energy of 220 to 300 kilowatts by energizing the coil segments 68a, 68b by means of the couplings 69a, 69b for a time of 130 to 220 sec each. The high level of induction energy is effective to substantially maintain the melted TiAl alloy thus formed away from the sidewalls of the casting vessel 54 as the above casting proceeds beneath the charging components to reduce the adverse reaction between the cast alloy and casting vessel material. As soon as the casting reaches the desired casting temperature (overheating) (for example approximately 1705.8 ° C after only about 3 minutes for the melting of Ti-6AI-4V), the container 20 already filled with an inert gas, such as argon, through the inlet 37 is lowered to insert the filling pipe 23 through the port 59a and also the port 102 inside the foundry M in the vessel 54, Figure 2. The container 20 is moved by the arm Hydraulically operated above mentioned (not shown). Before or during the immersion of the filling pipe 23 in the melt, a vacuum is drawn into the container 20 by means of the chamber 36. A vacuum is thus applied to the mold 22 compared to the atmospheric argon gas pressure in the foundry chamber 52 to establish a negative pressure differential between the mold cavities 24 and the melt in the vessel 54 to pull the melt up through the filling pipe 23 into the mold 22. The mold filled with melt 22 ( freshly removed from the melting chamber 52) is left in its container 20 and the flow of argon is provided through the inlet 37 so that the melt can solidify to / or cool under the argon gas at a temperature less than, for example, 426.6 ° C before the mold 22 is removed from the container 20. The following Examples are offered for the purposes of further illustrating and without limitation., the invention .

EXAMPLE 1 Casting the TiAl fusion: A refractory crucible coating material comprising mulite confronted with zirconia was used. The charge was fired in an argon atmosphere. The lower load component C 1 comprised of 12.23 kg of Ti in the form of a piece (flake pieces in pieces) and the top loading component C2 comprised of 6.79 kg in the form of grit mixed with the pieces of titanium. The initial energy input to an upper induction coil 68a for heating the charge component C2 was 190 kilowatts applied for 7 minutes. Then, the total energy input to the upper and lower induction coils 68a, 68b was applied at 200 kilowatts for 100 seconds to heat and melt the charging components C1 and C2 to achieve the melting temperature of approximately 1594.6 ° C. the total time to melt C1 and C2 was 520 seconds. The melt was cast in a counter-gravity vacuum at 45.72 cm Hg in the mold cavities 28 in the mold having zirconia facing with the mold embedded in mulita particles and using a steel filling tube.

EX EMPLO 2 Casting of the fusion of TÍ-6AI-4V: A refractory coating material of mithite crucible confronted with zirconia was used. The charge was melted in an argon atmosphere. The lower load component C1 comprised of 1 1 .32 kg of Ti in the form of a piece and 0.498 kg of vanadium in the form of grit. The top loading component C2 comprises 0.77 kg of Al in the form of shot with some pieces of titanium. The power input starts at an upper induction winding 68a to heat the load component Al was 190 kilowatts for 7.5 minutes. Then the total energy input to the upper and lower induction coils 68a, 68b was applied at 260 kilowatts for 172 seconds to heat and melt the charges C 1 and Ce to achieve the melting temperature of approximately 1705.8 ° C. The total time to melt loads C 1 and C 2 was 622 seconds. The smelter is evacuated in vacuum of 73.66 cm Hg in the mold container in 20 mold cavities having a zirconia front coating with the mold embedded in the mulita particles and using a steel filling tube. Although the invention has been shown and described with respect to certain embodiments thereof, those skilled in the art must understand that various changes, modifications, and omissions may be made in the form and detail thereof without departing from the spirit and scope of the invention. invention as set forth in the appended claims.

Claims (22)

1. CLAIMS 1 . A method of melting a reactive metallic material comprising at least a first metal having a first melting point and a second metal having a second melting point lower than the first melting point to form a molten alloy, which comprises: placing a first load component in the solid form and comprising the first metal in a refractory casting container behind a second load component in the solid form and comprising at least in part the second metal in the In this vessel, inductively and selectively heat the second charge component in said vessel to increase its temperature above that of the first charge component, and heat the second preheated charge component and the first charge component to a high input. of effective energy to produce the casting of the second preheated charge component followed by the casting of the first component of filler to form a molten alloy melt in said vessel. The method of claim 1, wherein it is included intercalating in said first loading component another metal having a melting point greater than that of the second metal. The method of claim 2, wherein the first loading component comprises pieces of the first metal placed near a bottom of the container and a mixture of the first metal and the other metal thereon. 4. The method of claim 1, which includes inserting in the second charge component another metal having a melting point higher or lower than that of the second metal. The method of claim 1, which initially includes feeding the induction coil means comprising the second charge component to heat it. 6. The method of claim 5, including feeding the induction coil means comprising the first and second load components to melt them. The method of claim 1, wherein the high energy input is effective to substantially hold the molten alloy away from the side wall of the container. The method of claim 1, wherein the first metal is selected from the group comprising titanium and zirconia. The method of claim 8, wherein the molten alloy is emptied from the container into a mold. 10. A method for casting a titanium-based alloy comprising aluminum and another metal having a higher melting point than that of aluminum to form a molten alloy, comprising: placing a first charge component in the form solid and comprising titanium and another metal in a refractory casting container behind a second loading component in the solid form and comprising at least part of aluminum in said container, inductively and selectively heating the second charge component in said vessel for increasing its temperature above that of the first charging component, and inductively heating the second charging component in the vessel to increase its temperature above that of the first charging component, and inductively heating the second charging component. pre-heated and the first charging component at high effective energy input to produce the second component melting of preheated charge followed by melting the first charge component to form a molten alloy melt in said container. eleven . The method of claim 10, which includes intercalating the titanium and the other metal as the first filler component. The method of claim 10, wherein the other metal is selected from the group consisting of vanadium, molybdenum, chromium, niobium, and silicon. The method of claim 10, which includes sandwiching the aluminum with another metal of lower or higher melting point as the second filler component. The method of claim 13, wherein the other lower melting metal comprises tin. 15. A method for melting a titanium-based alloy comprising aluminum and another metal having a lower melting point than that of aluminum to form a molten alloy, comprising: placing a first filler component in the solid form and comprising titanium in a refractory foundry vessel behind a second filler component in solid form and comprising at least in part aluminum and the other metal in said vessel, inductively and selectively heating the second filler component in said vessel to increase its temperature by above that of the first charging component, and inductively heating the second preheated charging component and the first charging component at a high effective energy input to produce the melting of the second preheated charging component followed by the melting of the first component charge to form a molten alloy melt in the container. The method of claim 15, which includes sandwiching the titanium and the metal having a higher melting point than that of the aluminum as the first filler component. The method of claim 16, wherein the metal is selected from the group comprising vanadium, molybdenum, chromium, niobium and silica. 18. The method of claim 16, wherein the other metal comprises tin. 19. Apparatus for melting a reactive metallic material comprising at least a first metal having a first melting point and a second metal having a second melting point lower than the first melting point to form a molten alloy, comprising: foundry vessel having a first charge component in solid form and comprising the first metal placed in the vessel under a second charge component in the solid form and comprising at least in part said second metal, and coil means of induction placed around said container and selectively energizable around said second charge component for selectively and inductively heating the second charge component in said container to increase its temperature over that of the first caga component, and then energizable around the first and second charge components for heating the second preheated charge component and the first charge component at high effective energy input to produce the melting of the second preheated charge component followed by the melting of the first charge component to form a molten alloy melt in said container. twenty-one . The apparatus of claim 19, wherein the induction coil means is selectively energizable about about 1/3 upper of the buffer vessel. twenty-one . The apparatus of claim 19, which includes electric conductor means connected to the induction means for selectively feeding them around the second charging component, the first and second coil conductors that are electrically powered by a source of electrical energy. 22. The apparatus of claim 21, including electrical conductor means connected to the induction coil means in a manner for feeding them around the first and second load components.